Automatic actuating mechanism

ABSTRACT

Fluidic mechanism is responsive to an event, for instance a contingency such as thread breakage in a sewing machine, to operate a control member whereby a clutch is actuated, for instance to disconnect a drive motor from the sewing machine. A transducer preferably in the form of a contractile bag is employed in the surveillant fluidic control circuit.

United States Patent Rockwell, Jr.

[ 1 June 27, 1972 [54] AUTOMATIC ACTUATING MECHANISM [72] Inventor: Adelbert W. Rockwell, Jr., Gloucester,

Mass.

[73] Assignee: USM Corporation, Boston, Mass.

[22] Filed: Aug. 3, 1970 21] App]. No.2 60,555

[52] US. Cl ..ll2/2l9 R, 192/88 R, 192/91 R,

192/125 C, 226/11, 242/37 [51] Int. Cl. ..D05b 69/36 [58] FieldofSearch ..112/2l8R,219R,219A,219B,

112/67; 192/91 R, 125 C, 128, 88 R, 56 F; 226/11, 37, 43; 242/37, 156.2; 139/370; 251/61 [56] References Cited UNITED STATES PATENTS 3,156,204 11/1964 Hamish et al. ..112/219 B Primary ExaminerH. Hampton Hunter Att0rney-Richard A. Wise, Richard B Megley and Carl E. Johnson [5 7] ABSTRACT Fluidic mechanism is responsive to an event, for instance a contingency such as thread breakage in a sewing machine, to operate a control member whereby a clutch is actuated, for instance to disconnect a drive motor from the sewing machine. A transducer preferably in the form of a contractile bag is employed in the surveillant fluidic control circuit.

2 Claims, 5 Drawing Figures PATENTEnJum 1812 3,672,315

sum 2 or 2 AUTOMATIC ACTUATING MECHANISM BACKGROUND OF THEINVENTION This invention pertains to automatically responsive means for controlling drive mechanism. It is frequently desirable upon the occurrence of some predetermined operation or contingency condition automatically to actuate or to deactuate other mechanism. By way of simple illustration, it is desirable automatically to stop a sewing machine or other threadusing device, from whichan operator maybe absent, when its thread breaks. Such automatic control of driving mechanism has hitherto been provided in various mechanical and mechano-electrical forms, one type commonly utilized in stitching machines, for instance, embodying a solenoid andplunger arrangementenergized'by breakage ofa thread. with its associated equipment, this and other known drive control arrangements have reliably worked automatically but commonly involve fairly complicated mechanisms and have not been inexpensive or easily maintained.

SUMMARY OF THE INVENTION 7 drive upon breakage of the thread being employed.

To these ends and in accordance with a feature of the invention, as illustrated herein, nonnally continuous flow of a small air stream is directed to a fluid control valve normally open when the thread in a swing machine is unbroken. Upon closure of the valve due to breakage of the thread a sensing transducer, desirably in the form of a venturi-coupled inflatable bag, connected to the air line is caused to expand thereby incurring axial contraction. This is converted to a force whereby, as shown herein, a clutch, actuating control member is shifted to its declutched position thus immediately stopping the machine.

It will be understood that the transducer operation can, if desired, simultaneously energize braking mechanism, or in other machines it may advantageously actuate or deactuate other control means of different types, and for immediate or predeterminedly delayed operation. It will further be appreciated that the illustrative arrangement can simultaneously exercise surveillance over 'more than a single thread when desired.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other features of the invention will now be more particularly described in connection with an illustrative embodiment, and with reference to the accompanying drawings thereof, inwhich:

FIG. I is a view in front elevation of a sewing machine incorporating an automatic drive control mechanism responsive to thread breakage, the machine being shown at rest; 7

FIG. 2 is an enlarged detail view of thread sensing means and valving associated therewith as shown in FIG. 1;

FIG. 3 is an enlarged vertical section taken through a clutch control box shown in FIG. I, the full lines showing the posit'ions of parts when the sewing machine is operative, and dash lines indicating the position of parts when it is at rest;

FIG. 4 is a view of the clutch control box shown in FIGS. 1 and 3, and indicating the rest and operative positions of acontrol member; and

FIG. 5 is an enlarged sectional view of a venturi coupled to the control means as shown in FIG. 3. t

DESCRIPTION OF THE PREFERRED EMBODIMENTS A sewing machine generally designated (FIG. 1) which may be of any conventional type, either industrial or domestic,

has a vertically reciprocable needle 12 driven through a clutch 14 from a motor 16 by means ofa pulley belt 18. A thread 20 is supplied to the needle from a supply mounted on a frame 24 of the machine which may be secured on a table 26. The thread 20 extends through a tensioningdevice 28 affixed to the frame 24 and through a thread monitoring or sensing means 30 (FIGS. I and 2) next to be described.

'As shown in FIGS. 1 and 2, the thread sensing means 30 is adjustably secured heightwise to the frame 24 by a set screw 32 extending through a vertical slot 34 (FIG. 2) in a plate 36. The plate 36 carries a fixed thread engaging pin 38, and a sensing lever 40 fulcrumedon a pivot pin 42.The thread normally extends progressively over the pins 42 and 38, being operatively maintained at all times under slight tension and in contact with these pins by a third or intermediate pin 44 pro jecting from an end of the lever 40, the third pin tending to depress the thread by reason of the influence of gravity on the lever 40. An abutment45 (FIG. 2) engageable with the lever 40 is formed on the plate 36 to limit upward movement of the lever. The right-hand end of the lever 40 is formed with a circular valve hub 46 (FIG. 2) concentric with the pivot pin 42, the hub being formed with a flat portion 48. The arrangement accordingly is such that a small continuous stream of air is normally emitted from a tube 50 at it open upper end adjacent to and spaced slightly from the flat 48 when horizontal as shown, but is blocked automatically and instantly by the circular valve hub 46 upon breakage of the thread 20. That is to say, consequent counterclockwise rotation of the lever 40 as effected by gravity enables the circumferential surface of the hub 46 to rotate into position to close off air exhaust from the tube 50. This is effective to operate sensing means as next explained.

An inlet air supply tube 52 (FIGS. 1, 3) has a nipple 54 (FIG. 5) threaded into a coupling 56 (FIGS. 1, 3, 5) mounted on a clutch control housing or'box 58, the orifice of the nipple 54 being larger than that of a nipple 60 interconnecting the tube 50 with the coupling 56. The tube'52 is connected to any suitable source of air under pressure. The box 58 is fixedly secured adjacent to the motor 16in a position to receive a transverse shaft 62 (FIGS. 3, 4) rotatable to control output of the clutch 14 by means of a shifter lever 64 (FIG. 1) and an interconnecting composite link 66 (FIGS. 1, 3). When the air exhaust via the tube 50 is closed off as above mentioned, pressure at once builds in the coupling 56 causing air flow via its passage 68 (FIG. 5) to inflate, and hence axially shorten, a transducer in the form of a bag-like part 70 (FIG. 3). For additional information concerning the structure of the part 70 reference may be had to copending application Ser. No. 867,463, filed Oct. 20, I969, in the name of John Yarlott. Axial change in dimension of the bag 70 controls the operating position of the shaft 62, the link 66, and the lever 64 as next described. A manual clutch reengaging lever 71 (FIGS. 1, 4) may also be secured on the shaft 62.

The open upper end of the bag 70 communicates with the passage 68, and the lower end of the bag is anchored in sealed relation to a protuberance 72 formed on a cross bar 74 secured in a pivotal latching pin 76 journaled in the box 58. As shown in FIG. 3 latching lever 78 secured on the shaft 62 and having an arm 79 connected to the link 66 is in its full line position when the machine 10 is operating, a lower portion 80 of the lever 78 then engaging a slabbed off shoulder 82 of the pin 76 under the influence of a return torsion spring 84. The latter is mounted on a hub portion of the lever 78 and has one end engaging the inside of the box 58 and its other extremity bearing on the depending arm of the lever 78 to urge it to return the shaft 62 to declutched position. It accordingly will be understood that upon thread breakage and consequent cessation of the air flow through the tube 50 and an increase in pressure in the passage 68, the bag 70 is caused to shorten axially to its dashed line position shown in FIG. 3 thereby moving the shaft 62 and hence stop further drive of the machine by the motor 16 through its clutch 14.

When an unbroken thread 20 is again led to the needle 12 and supports the lever 40 by engaging its pin 44 in the manner shown in FIG. 2, air from the tube 50 is again allowed to be vented therefrom by the repositioned flat 48. The tripped clutch 14 is manually shifted by means of the lever 71 back to its engaged or full time position shown in FIG. 3. Accordingly the transducer or bag 70, which may have flexible ribs extending lengthwise therein, becomes deflated and assumes its normal full length to restore the crossbar 74 to its full position in FIG. 3.

From the foregoing it will be appreciated that the sensing means 30 taken with the responsive contingency clutch control mechanism of FIG. 3 provides a simple, reliable, compact, and automatic device effective to declutch the machine drive. It will be understood that the invention may also be adapted in a particular machine, not necessarily one for sewing, to initiate its operation upon the sensing ofa selected event as well as to terminate a drive contingent upon the event.

Having thus described my invention, what I claim as new and desire to secure by Letters patent of the United States is:

1. In a sewing machine having a motor driven needle, a clutch shiftable between engaged and disengaged positions controlling the drive of the needle, means for supplying thread under tension to the needle, and fluid pressure controlled mechanism responsive to loss of thread tension for automatically shifting said clutch to disengaged position, said mechanism comprising a valve actuatable in response to change in the thread tension, the valve having a rotatable hub disposed adjacent to an air vent, a transducer responsive to operation of the valve, and linkage including a latching lever operatively interconnected between the transducer and the clutch, the arrangement being such that the valve hub has a flat portion disposed normally to allow passage of air from the vent and another portion disposed to impede such air passage upon a change in the thread tension.

2. A sewing machine as set forth in claim 1 wherein said valve hub is formed on a pivotal lever, and a portion of the lever is disposed to rest on the thread, under the influence of gravity, between two thread contacting localities over which the thread progressively passes. 

1. In a sewing machine having a motor driven needle, a clutch shiftable between engaged and disengaged positions controlling the drive of the needle, means for supplying thread under tension to the needle, and fluid pressure controlled mechanism responsive to loss of thread tension for automatically shifting said clutch to disengaged position, said mechanism comprising a valve actuatable in response to change in the thread tension, the valve having a rotatable hub disposed adjacent to an air vent, a transducer responsive to operation of the valve, and linkage including a latching lever operatively interconnected between the transducer and the clutch, the arrangement being such that the valve hub has a flat portion disposed normally to allow passage of air from the vent and another portion disposed to impede such air passage upon a change in the thread tension.
 2. A sewing machine as set forth in claim 1 wherein said valve hub is formed on a pivotal lever, and a portion of the lever is disposed to rest on the thread, under the influence of gravity, between two thread contacting localities over which the thread progressively passes. 